Process for making granular detergents

ABSTRACT

A process for making granular detergents is disclosed. In a first step, an aqueous slurry is formed. The aqueous slurry comprises anionic surfactant, chelating agents, at least 0.5%, by weight, of sodium aluminosilicate, and inorganic salts of a type which raise the ionic conductivity of the aqueous slurry. The aqueous slurry contains essentially no silicates and has a low viscosity suitable for spray-drying to form crisp, free-flowing powder. After being formed, the slurry is dried to form a particulate detergent composition.

The present invention relates to a process for preparing a particulatedetergent composition, in particular by spray drying an aqueous slurry.Particulate detergent compositions are also disclosed.

Many granular detergents which are sold commercially comprise sodiumaluminosilicate as the sole builder, or as a component of a buildersystem. It is known, for example from JP204098/1983, laid open on Nov.28th 1983, that heated aqueous slurries, such as those used inconventional spray-drying processes, which comprise both sodiumaluminosilicate and water-soluble silicate, cause insoluble complexes toform. These insoluble complexes are undesirable, in laundry detergentsbecause they can result in residues on washed fabrics. Furthermore,without the silicate to act as a powder structurant, the particle sizedistribution of the spray-dried powder may be unacceptably broad.

In the absence of water-soluble silicate in the aqueous slurry, variousother components have been proposed as powder structurants, useful toachieve a crisp, free-flowing spray-dried powder. Included amongst thepowder structurants that have been suggested are film-forming polymer:polycarboxylates (for example, U.S. Pat. No. 4,379,080); polyacrylates(for example, JP204098/1983); sucrose and derivatives (for example,EP-A-0 215 637); sodium sesquicarbonate (for example, EP-A-0 242 138).

However, unless the powder structurants are required by the formulatoras active ingredients, then they are an expensive processing aid.

An aqueous slurry which does not comprise either water-soluble silicate,or one of the alternative powder structurants is difficult to spray dry.In particular high water concentrations are generally needed in order tomaintain the viscosity of the slurry low enough to provide crisp,free-flowing particles of the desired particle size when spray-dried.The disadvantage of high water concentrations is that the excess watermust be removed during the drying step and a lot of energy is needed todo this.

WO90/04630, published on May 3rd, 1990, describes a process forpreparing a carbonate containing detergent slurry comprising analkylpolyglycoside and an alkali metal chloride. Zeolite A is suggestedas one possible builder albeit in the presence of silicate (at 7% byweight in Table VI).

The object of the present invention is to avoid residue problems bysubstantially omitting silicate from an aqueous slurry which comprisesanionic surfactant and aluminosilicate, and at the same time to providea low viscosity slurry suitable for spray-drying to form crisp,free-flowing powder.

SUMMARY OF THE INVENTION

According to the invention this object is achieved by forming an aqueousslurry comprising water, anionic surfactant and at least 0.5% by weightof sodium aluminosilicate and which further comprises less than 5% byweight of silicate and at least 1% by weight of an inorganic salt, or amixture of inorganic salts, and whereby the addition of the inorganicsalt increases the ionic conductivity of the aqueous slurry, andsubsequently drying the aqueous slurry to form the particulate detergentcomposition.

Preferably the inorganic salt is an alkali metal or alkaline earth metalsalt, or mixtures thereof of halide, nitrate or citrate, most preferablysodium chloride.

In a more preferred embodiment of the invention the step of adding theinorganic salt raises the ionic conductivity of the aqueous slurry by atleast 3 milliSiemens, and preferably by at least 5 milliSiemens.

A further aspect of the invention concerns spray-dried detergent powdercompositions. Preferred compositions comprise:

at least one surfactant, and preferably at least 5% by weight ofsurfactant most preferably from 5% to 20% of anionic surfactant;

from 2 to 80%, and preferably from 10% to 50% or from 1% to 50%,preferably 5% to 30% by weight of aluminosilicate;

from 1% to 50%, preferably 1% to 20%, more preferably from 1% to 10% byweight of an inorganic salt selected from the group consisting of alkalimetal halides, nitrates, citrates or mixtures thereof, and preferablyfrom 2% to 10% by weight of an alkali metal, preferably sodium,chloride; and

less than 5%, preferably less than 2% by weight of silicate.

DETAILED DESCRIPTION OF THE INVENTION

Essential components of the compositions of the present invention arealuminosilicate builders such as those having the empirical formula:

    M.sub.z (zAlO.sub.2).sub.y ]·x H.sub.2 O

wherein z and y are integers of at least 6, the molar ratio of z to y isin the range from 1.0 to about 0.5, and x is an integer from about 15 toabout 264.

Useful aluminosilicate ion exchange materials are commerciallyavailable. These aluminosilicates can be crystalline or amorphous instructure and can be naturally-occurring aluminosilicates orsynthetically derived. A method for producing aluminosilicate ionexchange materials is disclosed in U.S. Pat. No. 3,985,669, Krummel etal, issued Oct. 12, 1976. Preferred synthetic crystallinealuminosilicate ion exchange materials useful herein are available underthe designations zeolite A, zeolite P(B), zeolite MAP, zeolite X andzeolite Y. In an especially preferred embodiment, the crystallinealuminosilicate ion exchange material has the formula

    Na.sub.12 [(AlO.sub.2).sub.12 (SiO2).sub.12 ]·x H.sub.2 O

wherein x is from about 20 to about 30, especially about 27. Thismaterial is known as zeolite A. Dehydrated zeolites (x=0-10), and"overdried" zeolites (x=10-20) may also be used herein. The "overdried"zeolites are particularly useful when a low moisture environment isrequired, for example to improve stability of detergent bleaches such asperborate and percarbonate. Preferably, the aluminosilicate has aparticle size of about 0.1-10 micrometers in diameter. Preferred ionexchange materials have a particle size diameter of from about 0.2micrometers to about 4 micrometers. The term "particle size diameter"herein represents the average particle size diameter by weight of agiven ion exchange material as determined by conventional analyticaltechniques such as, for example, microscopic determination utilizing ascanning electron microscope. The crystalline zeolite A materials hereinare usually further characterized by their calcium ion exchangecapacity, which is at least about 200 mg equivalent of CaCO₃ waterhardness/g of aluminosilicate, calculated on an anhydrous basis, andwhich generally is in the range of from about 300 mg eq./g to about 352mg eq./g. The zeolite A materials herein are still further characterizedby their calcium ion exchange rate which is at least about 2 grains Ca⁺⁺/gallon/minute/gram/gallon (0.13 g Ca⁺⁺ /liter/minute/gram/liter) ofaluminosilicate (anhydrous basis), and generally lies within the rangeof from about 2 grains/gallon/minute/gram/gallon(0.13 g Ca⁺⁺/liter/minute/gram/liter) to about 6 grains/gallon/minute/gram/gallon(0.39 g Ca⁺⁺ /liter/minute/gram/liter), based on calcium ion hardness.Optimum aluminosilicate for builder purposes exhibit a calcium ionexchange rate of at least about 4 grains/gallon/minute/gram/gallon (0.26g Ca⁺⁺ /liter/minute/gram/liter).

The granular agglomerates of the present invention also comprise otherdetergent ingredients.

Water-soluble salts of the higher fatty acids, i.e., "soaps", are usefulanionic surfactants in the compositions herein. This includes alkalimetal soaps such as the sodium, potassium, ammonium, and alkylammoniumsalts of higher fatty acids containing from about 8 to about 24 carbonatoms, and preferably from about 12 to about 18 carbon atoms. Soaps canbe made by direct saponification of fats and oils or by theneutralization of free fatty acids. Particularly useful are the sodiumand potassium salts of the mixtures of fatty acids derived from coconutoil and tallow, i.e., sodium or potassium tallow and coconut soap.

Useful anionic surfactants also include the water-soluble salts,preferably the alkali metal, ammonium and alkylolammonium salts, oforganic sulfuric reaction products having in their molecular structurean alkyl group containing from about 10 to about 20 carbon atoms and asulfonic acid or sulfuric acid ester group. (Included in the term"alkyl" is the alkyl portion of acyl groups.) Examples of this group ofsynthetic surfactants are the sodium and potassium alkyl sulfates,especially those obtained by sulfating the higher alcohols (C₈ -C₁₈carbon atoms) such as those produced by reducing the glycerides oftallow or coconut oil; and the sodium and potassium alkyl benzenesulfonates in which the alkyl group contains from about 9 to about 15carbon atoms, in straight or branched chain configuration, e.g., thoseof the type described in U.S. Pat. Nos. 2,220,099 and 2,477,383; andmethyl ester sulphonates. Especially valuable are linear straight chainalkyl benzene sulfonates in which the average number of carbon atoms inthe alkyl group is from about 11 to 13, abbreviated as C₁₁ -C₁₃ LAS.

Other anionic surfactants herein are the sodium alkyl glyceryl ethersulfonates, especially those ethers of higher alcohols derived fromtallow and coconut oil; sodium coconut oil fatty acid monoglyceridesulfonates and sulfates; sodium or potassium salts of alkyl phenolethylene oxide ether sulfates containing from about 1 to about 10 unitsof ethylene oxide per molecule and wherein the alkyl groups contain fromabout 8 to about 12 carbon atoms; and sodium or potassium salts of alkylethylene oxide ether sulfates containing from about 1 to about 10 unitsof ethylene oxide per molecule and wherein the alkyl group contains fromabout 10 to about 20 carbon atoms.

Other useful anionic surfactants herein include the water-soluble saltsof esters of alpha-sulfonated fatty acids containing from about 6 to 20carbon atoms in the fatty acid group and from about 1 to 10 carbon atomsin the ester group; water-soluble salts of 2-acyloxy-alkane-1-sulfonicacids containing from about 2 to 9 carbon atoms in the acyl group andfrom about 9 to about 23 carbon atoms in the alkane moiety; alkyl ethersulfates containing from about 10 to 20 carbon atoms in the alkyl groupand from about 1 to 30 moles of ethylene oxide; watersoluble salts ofolefin sulfonates containing from about 12 to 24 carbon atoms; andbeta-alkyloxy alkane sulfonates containing from about 1 to 3 carbonatoms in the alkyl group and from about 8 to about 20 carbon atoms inthe alkane moiety.

Water-soluble nonionic surfactants are also useful as surfactants in thecompositions of the invention. Indeed, preferred processes useanionic/nonionic blends. Such nonionic materials include compoundsproduced by the condensation of alkylene oxide groups (hydrophilic innature) with an organic hydrophobic compound, which may be aliphatic oralkyl aromatic in nature. The length of the polyoxyalkylene group whichis condensed with any particular hydrophobic group can be readilyadjusted to yield a water-soluble compound having the desired degree ofbalance between hydrophilic and hydrophobic elements.

Suitable nonionic surfactants include the polyethylene oxide condensatesof alkyl phenols, e.g., the condensation products of alkyl phenolshaving an alkyl group containing from about 6 to 16 carbon atoms, ineither a straight chain or branched chain configuration, with from about4 to 25 moles of ethylene oxide per mole of alkyl phenol.

Preferred nonionics are the water-soluble condensation products ofaliphatic alcohols containing from 8 to 22 carbon atoms, in eitherstraight chain or branched configuration, with from 1 to 25 moles ofethylene oxide per mole of alcohol, especially 2 to 7 moles of ethyleneoxide per mole of alcohol. Particularly preferred are the condensationproducts of alcohols having an alkyl group containing from about 9 to 15carbon atoms; and condensation products of propylene glycol withethylene oxide.

Other preferred nonionics are polyhydroxy fatty acid amides which may beprepared by reacting a fatty acid ester and an N-alkyl polyhydroxyamine. The preferred amine for use in the present invention isN-(R1)-CH2(CH2OH)4-CH2-OH and the preferred ester is a C12-C20 fattyacid methyl ester. Most preferred is the reaction product of N-methylglucamine (which may be derived from-glucose) with C12-C20 fatty acidmethyl ester.

Methods of manufacturing polyhydroxy fatty acid amides have beendescribed in WO 9206073, published on Apr. 16th, 1992. This applicationdescribes the preparation of polyhydroxy fatty acid amides in thepresence of solvents. In a highly preferred embodiment of the inventionN-methyl glucamine is reacted with a C12-C20 methyl ester. It also saysthat the formulator of granular detergent compositions may find itconvenient to run the amidation reaction in the presence of solventswhich comprise alkoxylated, especially ethoxylated (EO 3-8) C12-C14alcohols (page 15, lines 22-27). This directly yields nonionicsurfactant systems which are suitable for use in the present invention,such as those comprising N-methyl glucamide and C12-C14 alcohols with anaverage of 3 ethoxylate groups per molecule.

Semi-polar nonionic surfactants include water-soluble amine oxidescontaining one alkyl moiety of from about 10 to 18 carbon atoms and 2moieties selected from the group consisting of alkyl groups andhydroxyalkyl groups containing from 1 to about 3 carbon atoms;water-soluble phosphine oxides containing one alkyl moiety of about 10to 18 carbon atoms and 2 moieties selected from the group consisting ofalkyl groups and hydroxyalkyl groups containing from about 1 to 3 carbonatoms; and water-soluble sulfoxides containing one alkyl moiety of fromabout 10 to 18 carbon atoms and a moiety selected from the groupconsisting of alkyl and hydroxyalkyl moieties of from about 1 to 3carbon atoms.

Ampholytic surfactants include derivatives of aliphatic or aliphaticderivatives of heterocyclic secondary and tertiary amines in which thealiphatic moiety can be either straight or branched chain and whereinone of the aliphatic substituents contains from about 8 to 18 carbonatoms and at least one aliphatic substituent contains an anionicwater-solubilizing group.

Zwitterionic surfactants include derivatives of aliphatic quaternaryammonium phosphonium, and sulfonium compounds in which one of thealiphatic substituents contains from about 8 to 18 carbon atoms.

Useful cationic surfactants include water-soluble quaternary ammoniumcompounds of the form R₄ R₅ R₆ R₇ N⁺ X⁻, wherein R₄ is alkyl having from10 to 20, preferably from 12-18 carbon atoms, and R₅, R₆ and R₇ are eachC₁ to C₇ alkyl preferably methyl; X⁻ is an anion, e.g. chloride.Examples of such trimethyl ammonium compounds include C₁₂₋₁₄ alkyltrimethyl ammonium chloride and cocalkyl trimethyl ammoniummethosulfate.

The granular detergents of the present invention can contain neutral oralkaline salts which have a pH in solution of seven or greater, and canbe either organic or inorganic in nature. The builder salt assists inproviding the desired density and bulk to the detergent granules herein.While some of the salts are inert, many of them also function asdetergency builder materials in the laundering solution.

Useful water-soluble salts include the compounds commonly known asdetergent builder materials. Builders are generally selected from thevarious water-soluble, alkali metal, ammonium or substituted ammoniumphosphates, polyphosphates, phosphonates, polyphosphonates, carbonates,silicates, borates, and polyhyroxysulfonates. Preferred are the alkalimetal, especially sodium, salts of the above.

Specific examples of inorganic phosphate builders are sodium andpotassium tripolyphosphate, pyrophosphate, polymeric metaphosphatehaving a degree of polymerization of from about 6 to 21, andorthophosphate. Examples of polyphosphonate builders are the sodium andpotassium salts of ethylene diphosphonic acid, the sodium and potassiumsalts of ethane 1-hydroxy-1,1-diphosphonic acid and the sodium andpotassium salts of ethane, 1,1,2-triphosphonic acid. Other phosphorusbuilder compounds are disclosed in U.S. Pat. Nos. 3,159,581; 3,213,030;3,422,021; 3,422,137; 3,400,176 and 3,400,148, incorporated herein byreference.

Examples of nonphosphorus, inorganic builders are sodium and potassiumcarbonate, bicarbonate, sesquicarbonate, tetraborate decahydrate, andsilicate having a molar ratio of SiO₂ to alkali metal oxide of fromabout 0.5 to about 4.0, preferably from about 1.0 to about 2.4.

Polymers

Also useful are various organic polymers, some of which also mayfunction as builders to improve detergency. Included among such polymersmay be mentioned sodium carboxy-lower alkyl celluloses, sodium loweralkyl celluloses and sodium hydroxy-lower alkyl celluloses, such assodium carboxymethyl cellulose, sodium methyl cellulose and sodiumhydroxypropyl cellulose, homo & co polymers of amino acids (particularlyhomo and co polymers of aspartic acid glutamic acid), polyvinyl alcohols(which often also include some polyvinyl acetate), polyacrylamides,polyacrylates and various copolymers, such as those of maleic andacrylic acids, in particular maleic/acrylic/vinyl alcohol terpolymers.Molecular weights for such polymers vary widely but most are within therange of 2,000 to 100,000. Other suitable polymers are polyamine N-oxidepolymers, copolymers of N-vinylpyrrolidone and N-vinylimidazole,polyvinylpyrrolidone polymers, polyvinyloxazolidones andpolyvinylimidazoles or mixtures thereof.

Polymeric polycarboxyate builders are set forth in U.S. Pat. No.3,308,067, Diehl, issued Mar. 7, 1967. Such materials include thewater-soluble salts of homo-and copolymers of aliphatic carboxylic acidssuch as maleic acid, itaconic acid, mesaconic acid, fumaric acid,aconitic acid, citraconic acid, methylenemalonic acid, methyl acrylicand PEG. In the present invention it is preferred that polymericpolycarboxylates are substantially omitted from the aqueous slurry. Bysubstantially omitted, less than 5% by weight of the aqueous slurry ispreferred, and less than 2% by weight is more preferred.

Inorganic Salts

Whilst the skilled person has a wide range of inorganic salts from whichto choose, it is an essential feature of the present invention that theinorganic salt should result in an increased ionic conductivity of theaqueous slurry. The ionic conductivity of the aqueous slurry depends notonly on the inorganic salt used, but also on the amount of inorganicsalt used, and also on the composition of the aqueous slurry. Halides,especially chlorides, nitrates and citrates have been found to beparticularly effective inorganic salts which when used at the preferredlevels, have the effect of increasing the ionic conductivity of theaqueous slurry. Carbonates and sulphates are less effective, and maywell cause a decrease in the ionic conductivity of the slurry. Withoutwishing to be bound by theory, it is believed that the higher ionicconductivity of the aqueous slurry suppresses the formation of highlyviscous surfactant phases which are subsequently difficult to dry. Bypromoting less viscous surfactant phases the aqueous slurry is morereadily formed into free-flowing, crisp particles having a good particlesize distribution.

Silicone Oils

Particulate suds suppressors may also be incorporated into the finishedcomposition by dry adding. Preferably the suds suppressing activity ofthese particles is based on fatty acids or silicones.

Optionals

Other ingredients commonly used in detergent compositions can beincluded in the compositions of the present invention. These includeflow aids, color speckles, bleaching agents and bleach activators, sudsboosters or suds suppressors, antitarnish and anticorrosion agents, soilsuspending agents, anionic and nonionic soil release agents, dyes,clays, flocculating agents, STS, fillers, optical brighteners,germicides, pH adjusting agents, nonbuilder alkalinity sources,hydrotropes, enzymes, enzyme-stabilizing agents, chelating agents,(including EDDS) and perfumes.

These optional ingredients, especially optical brighteners, may beincorporated either directly in the agglomerates herein or may becomponents of separate particles suitable for dry adding to theagglomerates of the present invention.

Processing

The aqueous slurry may be prepared by a batch or continuous process.Most conveniently a batch mixer, or "crutcher" is used in which thevarious detergent components or dissolved in, or slurried with, water.Typically the aqueous slurry contains from about 20% to about 60% byweight of water, in particular from about 30% to about 40% by weight ofwater. This is referred to as the crutcher mix moisture. In the processof the present invention, the order of addition of the inorganic saltand the other components of the aqueous slurry (or "crutcher mix") isnot considered to be critical. It is an essential feature of the presentinvention that the ionic conductivity of the aqueous slurry whichcomprises the inorganic salt must be greater than the ionic conductivityof the aqueous slurry in the absence of the inorganic salt. It ispreferred that the addition of the inorganic salt results in an aqueousslurry having an ionic conductivity which is at least 3 milliSiemenshigher than a corresponding aqueous slurry from which the inorganic salthas been omitted.

The drying of the aqueous slurry may be achieved by any one of severalprocesses known to the skilled man, but it is preferably prepared byspray drying. Following the spray drying route, an aqueous slurry isprepared comprising the solids. The slurry is then pumped at highpressure through atomising nozzles into a drying tower where excesswater is driven off, producing a flowable powder. The resulting powdermay then be oversprayed with liquid ingredients, especially nonionicsurfactants for which the powder has a high adsorption capacity beforeit loses its good flow characteristics. Other powdered components of thefinished laundry detergent may be dry mixed with the flowable powderproduced by the above process.

TEST METHOD Procedure for the Conductivity Test

1. Prepare a 15 kg sample of aqueous slurry ready for spray drying.

2. Place the sample in a large bucket 400 mm diameter and 500 mm inheight.

3. Let the mix cool to 30° C.

4. Using a Jenwat 4020 Conductivity Meter, measure the conductivity ofthe aqueous slurry.

EXAMPLES

    ______________________________________                                                  Aqueous Slurry Composition (% by weight)                                        Reference                                                                              Ex. 1   Ex. 2 Ex. 3 Ex. 4                                ______________________________________                                          LAS                     11.2       11.2   11.7    11.2    11.2                Zeolite A               26.2       26.2   30.0    26.2    26.2                Water                   33.0       33.0   34.5    33.0    33.0                Chelant                  0.3       0.3    0.3     0.3     0.3                 Brightener               0.1       0.1    0.1     0.1     0.1                 Magnesium Sulphate       0.3       0.3    0.3     0.3     0.3                 Carboxy Methyl           0.3       0.3    0.3     0.3     0.3                 Cellulose                                                                     HEDP                     0.3       0.3    0.3     0.3     0.3                 Copolymer of             0.4       0.4    0.4     0.4     0.4                 acrylic & maleic                                                              acid                                                                          Miscellaneous            2.2       2.2    2.3     2.2     2.2                 Sodium Sulphate         25.7       21.4   21.4    24.3    18.5                Sodium Chloride           0        4.3    1.4     7.2      0                  Sodium Citrate            0         0      0       0      4.3                 Conductivity              10        19     17      21      13                 (milliSiemens)                                                              ______________________________________                                                   Aqueous Slurry Composition (% by weight)                                        Ex. 5   Ex. 6   Ex. 7 Ex. 8 Ex. 9                                ______________________________________                                          LAS                     11.2      11.2     11.7     11.2     11.2                                                     Zeolite A               26.2                                                   26.2     30.0     26.2                                                      26.2                                   Water                   33.0      33.0     34.5     33.0     33.0                                                     Chelant                 0.3                                                    0.3       0.3      0.3                                                      0.3                                    Brightener              0.1       0.1       0.1      0.1      0.1                                                     Magnesium Sulphate     0.3                                                    0.3       0.3      0.3      0.3       Carboxy Methyl          0.3       0.3      0.3      0.3      0.3                                                      Cellulose                             HEDP                    0.3       0.3      0.3      0.3      0.3                                                      Copolymer of            0.4                                                    0.4      0.4      0.4      0.4       acrylic & maleic                                                              acid                                                                          Miscellaneous           2.2       2.2      2.3      2.2      2.2                                                      Sodium Sulphate        21.4                                                   21.4     21.4     21.4     21.4       Potassium Chloride     4.3       0        0        0        0                 Potassium Nitrate         0      4.3      0        0        0                 Potassium Citrate          0       0       4.3       0        0                                                       Calcium Chloride          0                                                    0        0       4.3       0                                                 Caicium Nitrate           0                                                    0        0        0      4.3                                                 Conductivity            19                                                      17       13       16       14       (milliSiemens)                                                              ______________________________________                                    

The aqueous slurry is heated to 70° C. and is fed through to a series ofpressure pumps. This increases the pressure of the mix up to 80 bar. Airis then injected into the mix at a pressure of 100 bar. The highpressure mix is then directed to the top of the spray drying tower. Hereit is blown through a set of nozzles, which range in aperture diameterup to 1 mm. These atomise the slurry into droplets. The moisture isdriven off these particles as they fall through the tower with aresidence time of up to 180 seconds by contact with hot air at 275° C.At the bottom of the tower a blown powder is collected with a density inthe range of 300-550 g/l. The resulting blown powder has a moisture inthe range of 5-15% with the majority of the particles having a size inthe range of 150-1200 micrometers.

We claim:
 1. A process for preparing a particulate detergent compositionwhich comprises:(a) forming an aqueous slurry comprising water, ananionic surfactant as the sole surfactant, chelating agents and at least0.5%, by weight, of sodium aluminosilicate and copolymers of acrylic andmaleic acid as the sole builders; (b) adding to the aqueous slurry aninorganic salt selected from the group consisting of:(i) alkali metalsalts of halides and nitrates; (ii) alkaline earth metal salts ofhalides and nitrates; and (iii) mixtures thereof; (c) drying theslurry;wherein the aqueous slurry comprises at least 1% by weight of theinorganic salt, and whereby the addition of the inorganic salt increasesthe ionic conductivity of the aqueous slurry, and wherein the aqueousslurry contains essentially no water-soluble silicate and theparticulate composition comprises from 5% to 20% by weight, of theanionic surfactant.
 2. A process according to claim 1 wherein the stepof adding the inorganic salt raises the ionic conductivity of theaqueous slurry by at least 3 milliSiemens.
 3. A process according toclaim 1 wherein the step of adding the inorganic salt raises the ionicconductivity of the aqueous slurry by a least 5 milliSiemens.
 4. Aprocess according to claim 1 wherein the inorganic salt is sodiumchloride.
 5. A process according to claim 1 wherein the range ofinorganic salt is 1% to 50% by weight.
 6. A process according to claim 1wherein the aqueous slurry comprises from 4.3% to 7.2% of inorganicsalt.
 7. A process according to claim 1 wherein the range of sodiumaluminosilicate is 1% to 50% by weight.
 8. A process according to claim7 wherein the range of sodium aluminosilicate is 5% to 30% by weight.